1. Technical Field
The present disclosure relates to an electrical storage device that is used for various electronic devices, industrial apparatuses, or apparatuses for automobiles, and includes both a conductive separator and an electrolytic solution. The present disclosure also relates to the separator and a manufacturing method of the electrical storage device.
2. Description of the Related Art
With increase in the frequencies of electronic devices, an electrolytic capacitor having a large capacity and excellent equivalent-series-resistance (hereinafter referred to as “ESR”) characteristics in a high frequency region is also demanded as one of the electronic storage devices. Recently, in order to reduce the ESR in such a high frequency region, a solid electrolytic capacitor that employs a solid electrolyte as the electrolyte has been studied and commercialized. The solid electrolyte, for example, includes a conductive polymer that has an electric conductivity higher than that of a conventional electrolytic solution. In order to respond to the needs for large capacity, a winding-type solid electrolytic capacitor has been commercialized which has the following structure: a conductive polymer is filled into a capacitor element that is formed by winding an anode foil and a cathode foil via a separator therebetween.
However, the above-mentioned solid electrolytic capacitor employs, as the electrolyte, only a solid electrolyte which has a low capability of repairing the dielectric oxide film. Therefore, compared with an electrolytic capacitor employing a conventional electrolytic solution, leak current tends to be increased and a short-circuit failure is apt to be caused by the occurrence of a dielectric oxide film defect in the solid electrolytic capacitor. Therefore, it is difficult to produce a capacitor having a high withstand voltage.
Meanwhile, in order to reduce the above-mentioned problem, a winding-type electrolytic capacitor employing, as the electrolyte, both of an electrolytic solution and a solid electrolyte made of a conductive polymer is proposed. This electrolytic capacitor employs, as a separator substrate, separator paper such as Manila paper or kraft paper, a porous film, and a synthetic fiber non-woven fabric. A capacitor element is formed in the following processes: the separator substrate is made conductive by a conductive polymer that is produced by chemical-oxidative-polymerizing a monomer using persulfate as the oxidant and dopant; and the separator made conductive (hereinafter referred to as “conductive separator”) is interposed between an anode foil and a cathode foil. The capacitor element produced in those processes is impregnated with an electrolytic solution and is used (for example, Unexamined Japanese Patent Publication No. H7-283086).